164 JOHN H. LOVELL 



single instance observed on the 26th, when a bee inspected an 

 empty umbel but failed to visit those containing syrup. After 

 they had found syrup on two of the umbels, they examined all 

 the others very thoroughly, and also other flowers in the garden 

 previously neglected. They discovered the syrup on the flowers 

 long before they did that which had dripped on a few leaves, 

 and the discovery of the latter was incidental to their visits to 

 the flowers. The bright coloration was clearly an advantage in 

 this instance in enabling honey-bees in large numbers to find the 

 odorless sweet syrup. Obviously highly specialized bees are much 

 better adapted for the purpose of such an experiment than the 

 common flesh-flies observed by Plateau. 



Plateau made many additional experiments in the course of 

 which he introduced odoriferous syrups into the flowers of 

 Lilium candidum L., Passijlora adenophylla Masters, CEnoihera 

 speciosa Nuttal, Linum perenne L., and Convolvulus septum L., 

 with the result that insects in variety were attracted. But it 

 is unnecessary to consider his experiences further since insects 

 in large numbers may also be attracted to conspicuous, neglected 

 flowers by means of an odorless sweet liquid. Since Plateau 

 knew that sugar syrup was odorless it is natural to inquire why 

 he failed to employ it in control experiments. On four occasions 

 he did introduce syrup of sugar into the flowers of Lilium can- 

 didum, in three instances into two flowers and in one instance 

 into six flowers. He says that, as he foresaw, syrup of sugar 

 without odor did not show any power of attraction. >° But a 

 small number of Diptera, as Syritta pipiens, Melanophora roralis, 

 Anthomyia radicum and Calliphora erythrocephala, did find the 

 syrup and profit by their discovery. No information is given 

 as to the length of time the flowers were under observation. 

 The number of visits received, however, was about the same as 

 in the case of Polygonum Convolvulus, when anisette was added 

 to eight groups of flowers on a very warm clear day. Certainly 

 the list of Diptera recorded gave promise that many visits 

 would have been received had the supply of syrup been continued 

 for a longer period. Lilium candidum is a campanulate flower 

 two or three inches long adapted to pollination by hawk-moths, 

 and it is easy to understand that some time might elapse before 

 the deeply concealed syrup was found by Hymenoptera. No 



s° " Recherches experimentales sur les fleurs entomophiles," etc., p. 19. 



